/*
 * ice4j, the OpenSource Java Solution for NAT and Firewall Traversal.
 *
 * Copyright @ 2015 Atlassian Pty Ltd
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.ice4j.attribute;

import org.ice4j.StunException;

/**
 * The REQUESTED-TRANSPORT attribute is used to allocate a TURN address of
 * certain transport protocol.
 *
 * In the original TURN specification, only UDP is supported. Support of TCP is
 * detailed in draft-ietf-behave-turn-tcp-07.
 *
 * @author Sebastien Vincent
 * @author Aakash Garg
 */
public class RequestedTransportAttribute extends Attribute {
	/**
	 * Attribute name.
	 */
	public static final String NAME = "REQUESTED-TRANSPORT";

	/**
	 * The length of the data contained by this attribute.
	 */
	public static final char DATA_LENGTH = 4;

	public static final byte UDP = 17;

	public static final byte TCP = 6;

	/**
	 * Transport protocol.
	 *
	 * 17 = UDP; 6 = TCP.
	 */
	byte transportProtocol = UDP;

	/**
	 * Constructor.
	 */
	RequestedTransportAttribute() {
		super(REQUESTED_TRANSPORT);
	}

	/**
	 * Compares two STUN Attributes. Attributes are considered equal when their
	 * type, length, and all data are the same.
	 * 
	 * @param obj
	 *            the object to compare this attribute with.
	 * @return true if the attributes are equal and false otherwise.
	 */
	@Override
	public boolean equals(Object obj) {
		if (!(obj instanceof RequestedTransportAttribute))
			return false;

		if (obj == this)
			return true;

		RequestedTransportAttribute att = (RequestedTransportAttribute) obj;
		if (att.getAttributeType() != getAttributeType() || att.getDataLength() != getDataLength()
		/* compare data */
				|| att.transportProtocol != transportProtocol)
			return false;

		return true;
	}

	/**
	 * Returns the human readable name of this attribute. Attribute names do not
	 * really matter from the protocol point of view. They are only used for
	 * debugging and readability.
	 * 
	 * @return this attribute's name.
	 */
	@Override
	public String getName() {
		return NAME;
	}

	/**
	 * Returns the length of this attribute's body.
	 * 
	 * @return the length of this attribute's value (8 bytes).
	 */
	@Override
	public char getDataLength() {
		return DATA_LENGTH;
	}

	/**
	 * Returns a binary representation of this attribute.
	 * 
	 * @return a binary representation of this attribute.
	 */
	@Override
	public byte[] encode() {
		byte binValue[] = new byte[HEADER_LENGTH + DATA_LENGTH];

		// Type
		binValue[0] = (byte) (getAttributeType() >> 8);
		binValue[1] = (byte) (getAttributeType() & 0x00FF);
		// Length
		binValue[2] = (byte) (getDataLength() >> 8);
		binValue[3] = (byte) (getDataLength() & 0x00FF);
		// Data
		binValue[4] = transportProtocol;
		binValue[5] = 0x00;
		binValue[6] = 0x00;
		binValue[7] = 0x00;

		return binValue;
	}

	/**
	 * Sets this attribute's fields according to attributeValue array.
	 * 
	 * @param attributeValue
	 *            a binary array containing this attribute's field values and
	 *            NOT containing the attribute header.
	 * @param offset
	 *            the position where attribute values begin (most often offset
	 *            is equal to the index of the first byte after length)
	 * @param length
	 *            the length of the binary array.
	 * @throws StunException
	 *             if attrubteValue contains invalid data.
	 */
	@Override
	void decodeAttributeBody(byte[] attributeValue, char offset, char length) throws StunException {
		if (length != 4) {
			throw new StunException("length invalid");
		}

		transportProtocol = attributeValue[offset];
	}

	/**
	 * Set the transport protocol.
	 * 
	 * @param transportProtocol
	 *            transport protocol
	 */
	public void setRequestedTransport(byte transportProtocol) {
		this.transportProtocol = transportProtocol;
	}

	/**
	 * Get the transport protocol.
	 * 
	 * @return transport protocol
	 */
	public int getRequestedTransport() {
		return transportProtocol;
	}
}
